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preprints:1997:ttp97-54 [2016/03/17 11:03] (current)
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 +====== TTP97-54 Two-loop QCD corrections to the heavy quark pair production     cross section in e+e- annihilation near the threshold  ====== 
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 +   <hidden TTP97-54  Two-loop QCD corrections to the heavy quark pair production     cross section in e+e- annihilation near the threshold  > We present the O(alpha_s) corrections to the cross section for the 
 + reaction e+e- --> gamma^* --> Q \bar Q in the energy region close to 
 + the threshold. We assume that the energy of the reaction is such that 
 + both the perturbative expansion in the strong coupling constant and 
 + expansion in the relative velocity of the heavy quarks can be used. 
 + We explicitly obtain terms O(alpha_s^2/beta^2, alpha_s^2/beta, 
 + alpha_s^2) in the relative correction to the threshold cross section. 
 + Using the ideas of asymptotic expansions, we demonstrate how an 
 + expansion of Feynman diagrams in the threshold region is constructed. 
 + From this analysis we obtain a matching relation between the vector 
 + current in full QCD and the quark--antiquark current in NRQCD at 
 + leading order in 1/m and the second order in the strong coupling 
 + constant. 
 + </hidden> 
 +|**Andrzej Czarnecki and Kirill Melnikov**  |  
 +|** Phys. Rev. Lett. 80 2531 1998  **  | 
 +| {{preprints:1997:ttp97-54.pdf|PDF}} {{preprints:1997:ttp97-54.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9712222|arXiv]]   | 
 +| |